Bernd Kubista

Total hip arthroplasty using imageless computer-assisted hip navigation: a prospective randomized study.

In a prospective randomized study of two groups of 65 patients each, we compared the acetabular component position when using the imageless navigation system compared to the freehand conventional technique for cementless total hip arthroplasty. The position of the component was determined postoperatively on computed tomographic scans of the pelvis. There was no significant difference for postoperative mean inclination (P = 0.29), but a significant difference for mean postoperative acetabular component anteversion (P = 0.007), for mean deviation of the postoperative anteversion from the target position of 15° (P = 0.02) and for the outliers regarding inclination (P = 0.02) and anteversion (P < 0.05) between the computer-assisted and the freehand-placement group. Our results demonstrate the importance of imageless navigation for the accurate positioning of the acetabular component.

Temsirolimus Inhibits Malignant Pleural Mesothelioma Growth In Vitro and In Vivo: Synergism with Chemotherapy

Introduction:Human malignant pleural mesothelioma (MPM) is an asbestos-related malignancy characterized by frequent resistance to chemotherapy and radiotherapy. Here, we investigated the feasibility of mammalian target of rapamycin (mTOR) inhibition by temsirolimus as an antimesothelioma strategy. Methods:Phosphorylation of mTOR (p-mTOR) was assessed by immunohistochemistry in MPM surgical specimens (n = 70). Activation of mTOR and impact of mTOR inhibition by temsirolimus was determined in MPM cell lines in vitro (n = 6) and in vivo as xenografts in severe combined immunodeficiency mice (n = 2) either as single agent or in combination with cisplatin. Results:Strong immunoreactivity for p-mTOR was predominantly detected in epitheloid and biphasic but not sarcomatoid MPM specimens while adjacent normal tissues remained widely unstained. Accordingly, all mesothelioma cell lines harbored activated mTOR, which was further confirmed by hyperphosphorylation of the downstream targets pS6K, S6, and 4EBP1. Temsirolimus potently blocked mTOR-mediated signals and exerted a cytostatic effect on mesothelioma cell lines in vitro cultured both as adherent monolayers and as nonadherent spheroids. Mesothelioma cells with intrinsic or acquired cisplatin resistance exhibited hypersensitivity against temsirolimus. Accordingly, cisplatin and temsirolimus exerted synergistic inhibition of the mTOR downstream signals and enhanced growth inhibition and/or apoptosis induction in mesothelioma cell lines. Finally, temsirolimus was highly active against MPM xenograft models in severe combined immunodeficiency mice both as a single agent and in combination with cisplatin. Conclusion:The mTOR inhibitor temsirolimus is active against mesothelioma in vitro and in vivo and synergizes with chemotherapy. These data suggest mTOR inhibition as a promising novel therapeutic strategy against MPM.

Microarray analysis identifies distinct gene expression profiles associated with histological subtype in human osteosarcoma

Osteosarcoma is the most common primary malignant bone tumour. Currently osteosarcoma classification is based on histological appearance. It was the aim of this study to use a more systematic approach to osteosarcoma classification based on gene expression analysis and to identify subtype specific differentially expressed genes. We analysed the global gene expression profiles of ten osteosarcoma samples using Affymetrix U133A arrays (five osteoblastic and five non-osteoblastic osteosarcoma patients). Differential gene expression analysis yielded 75 genes up-regulated and 97 genes down-regulated in osteoblastic versus non-osteoblastic osteosarcoma samples, respectively. These included genes involved in cell growth, chemotherapy resistance, angiogenesis, steroid- and neuropeptide hormone receptor activity, acute-phase response and serotonin receptor activity and members of the Wnt/ß-catenin pathway and many others. Furthermore, we validated the highly differential expression of six genes including angiopoietin 1, IGFBP3, ferredoxin 1, BMP, decorin, and fibulin 1 in osteoblastic osteosarcoma relative to non-osteoblastic osteosarcoma. Our results show the utility of gene expression analysis to study osteosarcoma subtypes, and we identified several genes that may play a role as potential therapeutic targets in the future.

Bacterial adherence to different components of total hip prosthesis in patients with prosthetic joint infection

PurposeThe purpose of our study was to evaluate and quantify the bacterial adherence to the different components of total hip prosthesis.MethodsThe bacterial load of 80 retrieved hip components from 24 patients was evaluated by counting of colony-forming units (CFU) dislodged from component surfaces using the sonication culture method.ResultsMicro-organisms were detected in 68 of 80 explanted components. The highest bacterial load was detected on the polyethylene liners, showing a significant difference in distribution of CFU between the liner and metal components (stem and cup). Staphylococcus epidermidis was identified as the pathogen causing the highest CFU count, especially from the polyethylene liner.ConclusionsResults of our study confirm that sonicate culture of the retrieved liners and heads, which revealed the highest bacterial loads, are reliable and sufficient for pathogen detection in the clinical diagnostic routine.

Qualitative α-defensin test (Synovasure) for the diagnosis of periprosthetic infection in revision total joint arthroplasty

Aims The diagnosis of periprosthetic joint infection (PJI) remains demanding due to limitations of all the available diagnostic tests. The synovial fluid marker, &agr;‐defensin, is a promising adjunct for the assessment of potential PJI. The purpose of this study was to investigate the qualitative assessment of &agr;‐defensin, using Synovasure to detect or exclude periprosthetic infection in total joint arthroplasty. Patients and Methods We studied 50 patients (28 women, 22 men, mean age 65 years; 20 to 89) with a clinical indication for revision arthroplasty who met the inclusion criteria of this prospective diagnostic study. The presence of &agr;‐defensin was determined using the qualitative Synovasure test and compared with standard diagnostic methods for PJI. Based on modified Musculoskeletal Infection Society (MSIS) criteria, 13 cases were categorised as septic and 36 as aseptic revisions. One test was inconclusive. Results The Synovasure test achieved a sensitivity of 69% and a specificity of 94%. The positive and negative likelihood ratios were 12.46 and 0.33, respectively. A good diagnostic accuracy for PJI, with an area under the curve of 0.82, was demonstrated. Adjusted p‐values using the method of Hochberg showed that Synovasure is as good at diagnosing PJI as histology (p = 0.0042) and bacteriology with one positive culture (p = 0.0327). Conclusion With its ease of use and rapid results after approximately ten minutes, Synovasure may be a useful adjunct in the diagnosis of PJI.

Comparison of synovial fluid, urine, and serum ion levels in metal-on-metal total hip arthroplasty at a minimum follow-up of 18 years

Diagnosis of adverse reactions to metal debris in metal‐on‐metal hip arthroplasty is a multifactorial process. Systemic ion levels are just one factor in the evaluation and should not be relied upon solely to determine the need for revision surgery. Furthermore, the correlation between cobalt or chromium serum, urine, or synovial fluid levels and adverse local tissue reactions is still incompletely understood. The hypothesis was that elevated serum and urine metal‐ion concentrations are associated with elevated local metal‐ion concentrations in primary total hip arthroplasties (THA) and with failure of metal‐on‐metal articulations in the long‐term. In our present study, we evaluated these concentrations in 105 cementless THA with metal‐on‐metal articulating surfaces with small head diameter at a minimum of 18 years postoperatively. Spearman correlation showed a high correlation between the joint fluid aspirate concentration of cobalt and chromium with the serum cobalt (r = 0.81) and chromium level (r = 0.77) in patients with the THA as the only source of metal‐ions. In these patients serum metal‐ion analysis is a valuable method for screening. In patients with more than one source of metal or renal insufficiency additional investigations, like joint aspirations are an important tool for evaluation of wear and adverse tissue reactions in metal‐on‐metal THA.

Effects of selenium coating of orthopaedic implant surfaces on bacterial adherence and osteoblastic cell growth

The aim of this study was to evaluate whether coating titanium discs with selenium in the form of sodium selenite decreased bacterial adhesion of Staphylococcus aureus and Staph. epidermidis and impeded osteoblastic cell growth. In order to evaluate bacterial adhesion, sterile titanium discs were coated with increasing concentrations of selenium and incubated with bacterial solutions of Staph. aureus (ATCC 29213) and Staph. epidermidis (DSM 3269) and stained with Safranin-O. The effect of selenium on osteoblastic cell growth was also observed. The adherence of MG-63 cells on the coated discs was detected by staining with Safranin-O. The proportion of covered area was calculated with imaging software. The tested Staph. aureus strain showed a significantly reduced attachment on titanium discs with 0.5% (p = 0.011) and 0.2% (p = 0.02) selenium coating. Our test strain from Staph. epidermidis showed a highly significant reduction in bacterial adherence on discs coated with 0.5% (p = 0.0099) and 0.2% (p = 0.002) selenium solution. There was no inhibitory effect of the selenium coating on the osteoblastic cell growth. Selenium coating is a promising method to reduce bacterial attachment on prosthetic material.

Galectin-3 Induces a Pro-degradative/inflammatory Gene Signature in Human Chondrocytes, Teaming Up with Galectin-1 in Osteoarthritis Pathogenesis

Inflammatory chemo- and cytokines and matrix-degrading proteases underlie the progression of osteoarthritis (OA). Aiming to define upstream regulators for these disease markers, we pursued initial evidence for an upregulation of members of the adhesion/growth-regulatory galectin family. Immunohistochemical localization of galectin-3 (Gal-3) in sections of human cartilage with increasing levels of degeneration revealed a linear correlation reaching a chondrocyte positivity of 60%. Presence in situ was cytoplasmic, the lectin was secreted from OA chondrocytes in culture and binding of Gal-3 yielded lactose-inhibitable surface staining. Exposure of cells to the lectin led to enhanced gene expression and secretion of functional disease markers. Genome-wide transcriptomic analysis broadened this result to reveal a pro-degradative/inflammatory gene signature under the control of NF-κB. Fittingly, targeting this route of activation by inhibitors impaired the unfavourable response to Gal-3 binding, as also seen by shortening the lectin’s collagen-like repeat region. Gal-3’s activation profile overlaps with that of homodimeric galectin-1 (Gal-1) and also has distinctive (supplementing) features. Tested at subsaturating concentrations in a mixture, we found cooperation between the two galectins, apparently able to team up to promote OA pathogenesis. In summary, our results suggest that a network of endogenous lectins is relevant for initiating this process cascade.

Primary cementless total hip arthroplasty with second-generation metal-on-metal bearings: a concise follow-up, at a minimum of seventeen years, of a previous report.

BACKGROUND Second-generation, metal-on-metal bearings were introduced in 1988, to reduce wear and avoid polyethylene particle-induced osteolysis from total hip arthroplasty. In 2007, we reported the long-term results of ninety-eight patients (105 hips) who underwent primary cementless total hip arthroplasty involving the use of a prosthesis with a high-carbide-concentration, metal-on-metal articulating surface between November 1992 and May 1994. The present study gives an update on this patient cohort. METHODS At a minimum of seventeen years postoperatively, forty-nine patients (fifty-two hips) were available for follow-up examination. We retrospectively evaluated clinical and radiographic results as well as serum metal concentration. The mean patient age at the time of the index arthroplasty was fifty-six years. RESULTS Three cups (6% of the hips) and one stem (2% of the hips) were revised because of aseptic loosening of the implants combined with focal osteolysis. At the time of the latest follow-up evaluation, the mean Harris hip score was 88.8 points, and the mean University of California Los Angeles (UCLA) activity score was 6.7 points. The cumulative rate of implant survival, with aseptic failure as the end point, was 93.0% at 18.8 years. The median serum cobalt concentration in patients whose hip implant was the only source of cobalt was 0.70 μg/L (range, 0.4 to 5.1 μg/L), showing no increase in the value as noted at a minimum of ten years of follow-up. CONCLUSIONS The clinical and radiographic results of our study, which, to our knowledge, represent the longest duration of follow-up for a series of cementless total hip arthroplasties with use of a 28-mm metal-on-metal bearing, continue to be comparable with the results observed for other hard-on-hard bearings.

EGFR is not a major driver for osteosarcoma cell growth in vitro but contributes to starvation and chemotherapy resistance

BackgroundEnhanced signalling via the epidermal growth factor receptor (EGFR) is a hallmark of multiple human carcinomas. However, in recent years data have accumulated that EGFR might also be hyperactivated in human sarcomas. Aim of this study was to investigate the influence of EGFR inhibition on cell viability and its interaction with chemotherapy response in osteosarcoma cell lines.MethodsWe have investigated a panel of human osteosarcoma cell lines regarding EGFR expression and downstream signalling. To test its potential applicability as therapeutic target, inhibition of EGFR by gefitinib was combined with osteosarcoma chemotherapeutics and cell viability, migration, and cell death assays were performed.ResultsOsteosarcoma cells expressed distinctly differing levels of functional EGFR reaching in some cases high amounts. Functionality of EGFR in osteosarcoma cells was proven by EGF-mediated activation of both MAPK and PI3K/AKT pathway (determined by phosphorylation of ERK1/2, AKT, S6, and GSK3β). The EGFR-specific inhibitor gefitinib blocked EGF-mediated downstream signal activation. At standard in vitro culture conditions, clinically achievable gefitinib doses demonstrated only limited cytotoxic activity, however, significantly reduced long-term colony formation and cell migration. In contrast, under serum-starvation conditions active gefitinib doses were distinctly reduced while EGF promoted starvation survival. Importantly, gefitinib significantly supported the anti-osteosarcoma activities of doxorubicin and methotrexate regarding cell survival and migratory potential.ConclusionOur data suggest that EGFR is not a major driver for osteosarcoma cell growth but contributes to starvation- and chemotherapy-induced stress survival. Consequently, combination approaches including EGFR inhibitors should be evaluated for treatment of high-grade osteosarcoma patients.